shadowsocks的Tcp连接优化包含以下三种方式，分别是增大打开的文件描述符，打开快速端口重用和连接，增大队列缓冲区，为TCP连接延迟选择最优算法，比如BBR等
增大打开的文件描述符
vi /etc/security/limits.conf
添加这两行
* soft nofile 51200
* hard nofile 51200
然后, 在启动shadowsocks服务器之前,先设置ulimit
ulimit -n 51200
打开内核参数
- 快速重用端口和连接
- 队列和缓冲区增加到最大
- 为Tcp连接的延迟和高吞吐量选择最优算法
/etc/sysctl.conf
fs.file-max = 51200
net.core.rmem_max = 67108864
net.core.wmem_max = 67108864
net.core.netdev_max_backlog = 250000
net.core.somaxconn = 4096
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 0
net.ipv4.tcp_fin_timeout = 30
net.ipv4.tcp_keepalive_time = 1200
net.ipv4.ip_local_port_range = 10000 65000
net.ipv4.tcp_max_syn_backlog = 8192
net.ipv4.tcp_max_tw_buckets = 5000
net.ipv4.tcp_fastopen = 3
net.ipv4.tcp_mem = 25600 51200 102400
net.ipv4.tcp_rmem = 4096 87380 67108864
net.ipv4.tcp_wmem = 4096 65536 67108864
net.ipv4.tcp_mtu_probing = 1
net.ipv4.tcp_congestion_control = hybla
重载配置文件
sysctl -p